1. Field of the Invention
The present invention relates to a self-adhesive, flexible sealing tape on the basis of a flexible, self-adhesive core enveloped or coated with a second adhesive system, especially for adhesive bonding of vapour barrier films and vapour retarder films, as well as to processes for its manufacture.
2. Description of the Prior Art
A normal construction material moisture is unavoidable, but permanent moisture penetration of structural members in or at constructions should by all means be avoided as it frequently leads to damage.
Moisture can penetrate the constructions or structural members from the outside, mostly where a structural member is broken, blocked, torn or incomplete. Thus, a facade, for example, may become penetrated with moisture within a short time span if an eaves gutter is clogged or leaky, if roofing tiles are broken or have shifted, if connections of chimneys or skylights are defective, if there are cracks in the external plaster, or if sealings are flawed or even missing altogether.
Frequently, however, moist spots in structural members also occur because of humidity condensating at cold spots. The condensed water vapour is called “condensation water”. Under certain climatic conditions, humidity in the air of a room can condensate as condensation water on wall, ceiling and floor areas either on the surfaces of or within structural members. This leads to structural elements, especially insulation material, penetrated with water, to reduced heat insulation, formation of mould, and, ultimately, to more severe structural damage.
To avoid condensation water, it is sometimes sufficient to change ones heating and ventilation habits in the rooms concerned so that no additional damage occurs. In the event of damage, sometimes extensive rehabilitation measures are necessary, however, to prevent occurrence of condensation water in the future.
To protect the bricking and the insulating material, either in new buildings or when rehabilitation measures are carried through, a vapour barrier or a vapour retarder is installed which prevents condensation water from accumulating, for example, behind an interior insulation. The humidity of the room air can then no longer reach the insulating material. In the case of roof insulations, a vapour barrier or vapour retarder at the same time increases wind proofness.
Vapour barriers and vapour retarders usually consist of films such as PVC films, PE films (polyethylene) or aluminium foils. But roofing cardboard is utilised as well. However, plasters, cardboards, wood, as well as gypsum plaster boards or derived timer boards are also suitable for constructing durable and continuous, air-tight layers.
When using vapour barrier films and vapour retarder films, these must be bonded to substrates such as concrete, bricking, plaster, rough-sawn timber and the like in such a manner that a durable seal is obtained, to be able to lastingly fulfill their sealing function. In this regard, joints in the brickwork are a particular problem.
The bond of the vapour barrier film or vapour retarder film should be permanently elastic to be able to compensate the movements of the building. A further demand is ageing resistance of the bonds, and the market also wants the adhesives to be free of solvents, environmentally harmless and immediately adhesive.
To date, vapour barrier films and vapour retarder films have been bonded using a dispersion-based cartridge adhesive. In particular, attachment of a vapour barrier film to a wall could heretofore be realised exclusively with cartridge adhesives. These cartridge adhesives are free of solvent, but, depending on ambient conditions, they develop a stable adhesion only after more than 20 minutes, sometimes taking more than 24 hours. In addition, these cartridge adhesives are subject to the risk of degrading upon subsequent access of moisture.